Condenser for circuit interrupter causing flow of condensible gas



y 2, 1968 H. H. FAHNOE 3,391,368

CONDENSER FOR CIRCUIT INTERRUPTER CAUSING FLOW 0F CONDENSIBLE GAS Filed Jan. 22, 1968 3 Sheets-Sheet z H. H. FAHNOE CONDENSER FOR CIRCUIT INTERRUPTER CAUSING July 2, 1968 FLOW OF CONDENSIBLE. GAS

3 Sheets-Sheet 5 Filed Jan. 22, 1968 a I m 9 8 Z w m .J .J M, o 7 8 m m. a 0 M I \l..\w v km 7 United States Patent "ice 3 391,368 CONDENSER FOR CIRCUIT INTERRUPTER CAUSING FLGW OF CONDENSIBLE GAS Harold H. Fahnoe, Evanston, 11]., assignor to S & C Electric Company, Chicago, 11]., a corporation of Delaware Filed Jan. 22, 1968, Ser. No. 699,654 17 Claims. (Cl. 337-203) ABSTRACT OF THE DISCLOSURE Condenser for gas from a fuse has an are products director interposed between sections of heavy wire screen in a housing.

This invention is an improvement over the constructions disclosed in Lindell UJS. Patent 3,230,331, issued Jan. 18, 1966.

Among the objects of this invention are: To increase substantially the effectiveness of the construction of the aforesaid patent without substantially increasing the over all physical size thereof for a given rated fuse duty; to permit a substantial increase in the fault interrupting capacity of a solid material type fuse by equipping it with a gas and arc products condenser capable of handling the increased discharge due to the interruption of higher fault current; to increase substantially the number of maximum severity operations that can be withstood by a gas and are products condenser used for receiving the same to reduce noise and emission of gas and metallic particles to the atmosphere at a given duty; to interpose between the heavy wire screen sections in a housing or a shell arranged to receive the gas and are products from a solid material type fuse, an are products director or are transfer terminal having longitudinal openings for directing and distributing the exhaust flow of the gas and arc products into the wire screen therebelow, capable of absorbing a substantial portion of the energy therein, and thereby reducing erosion and vaporization of the wire screen sections; to transfer and hold the arc root substantially centrally of the director or are transfer terminal by providing a pocket therein opening centrally thereof toward the source of the exhaust flow along the rim of which the arc root tends to remain; and to restrict and position the individual openings in the are products director to avoid high back pressure in the fuse unit on high current interruption by permitting and distributing free total flow of the gas and arc products through the several openings into the wire screen section therebelow while preventing direct impingement from the fuse bore of these products and transfer of the arc root onto this wire section.

According to this invention a high thermal capacity good heat conductivity gas or are products director is interposed between heavy wire screen sections in a housing or shell of a condenser or muffler secured to the discharge end of a solid material type fuse that may be called upon to interrupt alternating fault current flow of the order of several thousands of amperes. Because of the shape and construction of the director it acts both as an arc transfer terminal and as a shield for the wire screen section on which it rests. The director has openings through it which are so shaped as to permit free flow of gas and are products therethrough to distribute them relatively uniformly and with a smooth flow pattern into this wire screen section with the result that high back pressure in the fuse bore is not developed. A pocket or cavity is provided in the central portion of the director and it opens toward the source of the arc establishing means to hold the arc root transferred thereto in the vicinity thereof thereby preventing its impingement on and accompanying erosion of the sections of wire screen.

3,391,368 Patented July 2, 1968 In the drawings: FIG. 1 is a perspective view of a circuit interrupter in which the present invention is embodied. FIGS. 2A and 2B, taken together with the former placed above the latter, show a vertical longitudinal sectional view through the circuit interrupter illustrated in FIG. 1 and through a portion of the condenser therefor, the remaining portion of the condenser being shown in elevation. FIG. 3 is a vertical sectional view, at an enlarged scale, showing the details of construction of the condenser or mother shown in FIG. 23. FIG. 4 is a bottom plan view of the condenser shown in FIG. 3. FIG. 5 is a top plan view of the gas or are products director. FIG. 6 is a bottom plan view of the director. FIG. 7 is a view, similar to FIG. 3, and shows another embodiment of the condenser or muffler. FIG. 8 is a top plan view of the gas or are products director in FIG. 7. FIG. 9 is a horizontal sectional view taken generally along the line 9-9 of FIG. 7.

Referring now particularly to FIG. 1 of the drawings, it will be observed that the reference character 10 designates a base which may be a metal base carrying upper and lower insulators 1'1 and 12. It will be understood that the length of the insulators .11 and 12 and their spacing apart depend upon the voltage of the system with which the present invention is employed. Upper and lower line contact clips 13 and 14 are carried by the insulators 11 and 12 at their outer ends for detachably receiving upper and lower terminals 15 and 16 that are mounted on the upper and lower ends of a tubular insulating housing or fuse holder 17 of a circuit interrupter that is indicated, generally, at 18. Associated with the lower terminal 16 is a condenser or muffier 19 in which the present invention is embodied.

As shown in FIGS. 2A-2B a coil tension spring 21 and a flexible cable or conductor 22 interconnect the upper terminal 14 and a spring and cable fastener 23 which forms a part of a replaceable cartridge, shown generally at 24. The replaceable cartridge 24 includes a rod-like terminal 25 which is connected at its upper end to the spring and cable fastener 23 and moves therewith upwardly under the influence of the coil tension spring 21 when it is released. At the lower end of the rod-like terminal 25 there is a fusible element 2-6 which is connected to a terminal fitting 27 that extends radially inwardly from a stationary terminal 28 at the lower end of the cartridge 24. The rod-like terminal 25 moves upwardly through a bore 29 that is formed in a body 30 of arc extinguishing material which may be boric acid or other water containing dielectric material. In parallel with the rod-like terminal 25 and fusible element 26 is a strain element assembly 31. It is connected at its upper end to the spring and cable fastener 23 and extends through an auxiliary bore 32 in the body 30 of arc extinguishing material and is connected at its lower end to a strain element pin 33 that extends radially inwardly from the stationary terminal 28. The lower end of the cartridge 24 is closed by a frangible disc 34 that is held in place by a snap lock spring 35. Connection between the terminal 28 and the lower terminal 16 is provided by contact fingers 36 de pending from the latter and engaging the periphery of the former. The lower ends of the contact fingers 36 abut a locking ring 37 threaded on the terminal 28.

When a circuit interrupter of the type illustrated at 1 8 and described hereinbefore operates to interrupt the flow of alternating fault current, particularly a relatively heavy fault current, a large amount of water vapor or gas is evolved from the bore 29 in the body 30 of arc extinguishing material. This vapor or gas together with are plasma at extremely high temperature and pressure flows through the bore 29 and out of the lower end of the cartridge 24. The frangible disc 34 initially is promptly expelled along with the metal vapors and are plasma incident to the blow.

ing of the fusible element 25 and release of the strain element assembly 31 which permit the spring 21 to retract the rod-like terminal 25 into the bore 29. When these are products are permitted to flow directly to the atmosphere, no particular interruption problem is involved although care must be taken that the part of the highly ionized are core that usually extends below the discharge end of the fuse cartridge 24 does not cause an external fault to another circuit or to ground or that the incident shock wave is not too severe in enclosed installations. When the circuit interrupter 18 is mounted within a relatively small enclosure, provision is made, according to this invention, by mounting the condenser 19 on the lower terminal 16 for confining the are to the inner end of the condenser 19 and for limiting the discharge of are products during the relatively short critical period when the high temperatures and pressures tend to be created with the result that the shock waves incident thereto are reduced to such an extent at a given current level that an ordinary enclosure can withstand them and the conductivity of the exhaust products is lowered so that large clearances or insulating shields are not necessary within such enclosure except at the very highest levels considerably in excess of the capabilities of the constructions disclosed in the above identified patent.

The condenser or mufiler 19 includes an adapter 38, which may be formed of brass, having an internal thread 39 for cooperation with an external thread on the lower terminal 16. The adapter 38 has an external thread 40 to receive the upper end of an elongated cylindrical shell 41. The adapter 38 also has a conical surface 42 for engaging the contact fingers 36 and clamping them against the terminal 28.

FIGS. 3, 4, and 6 show more clearly the details of construction of the elongated condenser or mutfier 19 which is specially designed and proportioned for use with a fuse type circuit interrupter 18 having a continuous current rating of 200 amperes, a voltage rating of 15,000 volts and an interrupting rating at this voltage of 20,000 amperes. Here it will be observed that the adapter 38 is threaded into the upper end of the elongated cylindrical shell 41 which is formed of suitable high strength metal. Retaining pins 43 extend along the threads 40 to hold the shell 41 against rotation relative to the adapter 38. The adapter 38 has a central depending flange 44 the outer surface 45 of which is conical for a purpose that will be apparent presently. The lower end of the shell 41 is slotted transversely as indicated at 46 for receiving a bar to facilitate the application or removal of the condenser 19 to or from terminal 16 at the lower end of the circuit interrupter 18. The extreme lower end 47 of the shell 41 is deformed inwardly to hold in place a cover disc or closure 48 that may be formed of hot rolled steel plate. The upper peripheral surface of the cover disc or closure 48 bears against an annular shoulder 49 which is formed along the inner wall of the shell 41 and against which the cover disc or closure 48 is held when the lower end 47 is inturned. Exhaust ports 50, of which there may be eight in number as shown in FIG. 4, are formed in the cover disc or closure 48 to provide a communication to the atmosphere.

At the upper end of the shell 41 there is positioned a first annular section 54 of wire screen. The section 54 of wire screen is relatively short and is formed of high heat conductivity relatively rigid convolutely wound 5 mesh wire screen that is formed by interweaving lengthwise extending wires and circularly extending wires of copper. The arrangement is such that a large diameter passageway 57 is provided centrally of the shell 41 and in alignment with and of larger diameter than the discharge opening 58 through the terminal 28. The conical surface 45 of the central depending flange 44 fits snugly into the upper end of the passageway 57. The large diameter passageway 57 provides a large area for receiving the initial blast from the circuit interrupter 18 on blowing of the fusible element 26 and the strain element assembly 31. As shown, in FIG. 3

4 the outer periphery of the first wire screen section 54 is juxtaposed to the inner surface of the shell 41 and thus substantially fills the cross section thereof except for the large diameter passageway 57.

Below and spaced slightly from the first wire screen section 54 is a second annular section 60 of wire screen which is substantially longer than the first section 54 and is formed in the same manner by convolutely winding relatively heavy wire screen of the same size as referred to above. The second wire screen section 60 is formed with a small diameter opening 63 therethrough which is substantially filled by a metallic stud 64 that preferably is formed of good heat conducting metal such as silicon bronze rod. The outer periphery of the second wire screen section 60 is such as to fit snugly against the inner surface of the shell 41 while the diameter of the opening 63 is such that the inner periphery fits snugly against the outer surface of the metallic stud 64. Except for the metallic stud 64 the second wire screen section 60 substantially fills the cross section of the lower end of the shell 41.

At its lower end the metallic stud 64 has a reduced diameter section 65 that extends through a central opening 66 in the cover disc or closure 48. The outer end is peened over as indicated at 67 to secure the metallic stud 64 to the cover disc or closure 48.

With a view to absorbing a substantial amount of heat energy from the are products that flow through the large diameter passageway 57 from the circuit interrupter 18 on operation thereof and for protecting the wire screen section 54 and especially the wire screen section 60 from erosion due to impingement thereon of the high temperature gas and are products or transfer of the lower arc root thereto, there is provided between the juxtaposed ends of the wire screen sections 54 and 60 a gas or are products director that is indicated, generally, at 68. It is shown in cross section in FIG. 3 and in more detail in FIGS. 5 and 6. The gas or are products director 68 preferably is formed of high heat conductivity cast copper alloy and has a rela tively great heat capacity. Accordingly, it is capable of absorbing a relatively great amount of heat energy from the arc and withstanding the blast of gas and are products without excessive erosion or vaporization. Also the director 68 provides momentarily a terminal for the root of the are that may be transferred to it from the terminals 27 and 28 of the fuse type circuit interrupter 18 by the blast of are products and magnetic forces as the arc extends in hairpin fashion from these terminals.

The configuration of the gas or are products director 68 is important. It has a central generally truncated conical section 69 which is in alignment with the discharge opening 58 through the terminal 28 and which in the lower capacity rating (200 amperes) projects a substantial distance into the lower end of the large diameter passageway 57. The conical section 69 is threaded at 70 for receiving a threaded reduced diameter upper end 71 of the stud 64. The director 68 also has a rim 72 that is generally trapezoidal in cross section with a generally cylindrical outer surface 73 which is juxtaposed to the inner surface of the shell 41. Openings 74 are formed in the director 68 between radially extending ribs 75 which taper from base sections 76 adjacent the upper end of the wire screen section 60 to curved upper ends 77. The cross sectional configuration of the director 68, as shown in FIG. 3, has a generally arcuate shape 78 along the upper end for the purpose of providing together with the tapered ribs 75 a streamline flow for the gas and are products that are discharged through the large diameter passageway 57 in the first wire screen section 54. The lateral dimension of each of the openings 74 along their pitch circle 79,

FIG. 5, is not substantially greater than the longitudinal dimension of each opening 74 at the pitch circle 79 for the purpose of preventing the are from looping downwardly past the ribs 75 and impinging on the upper end of the screen section 60. However, the area of the openings 74 is such as to permit sufiicient flow therethrough of the gas and arc products that the back pressure in the bore 29 of the circuit interrupter 18 does not become excessive.

It is important that the arc root or the terminal of the arc drawn on blowing of the fusible element 26 and strain element assembly 31 that is blown into the condenser or muffler 19 remain on the gas or arc products director 68 and particularly on the central section 69 thereof to minimize erosion of the annular sections 54 and 60 of wire screen. It is for this purpose that the upper end 80 of the stud 64 is spaced from the upper end of the threaded opening 70, thereby providing a cavity or pocket 81 along the periphery of which there is a great tendency for the arc root or terminal to locate in contradistinction to the outer surface of the central section 69 or any other part of the gas or are products director 68 or of the annular sections 54 and 60 of wire screen.

In FIG. 6 the broken line circle 82 encloses the area of the central section 69 adjacent the second section 60 of wire screen. This area is about the same as the area of the discharge opening 58 through the terminal 28, FIG. 2B. This relationship minimizes the impingement of the arc products onto the upper end of this wire screen section.

In assembling the elongated condenser or muffler 19, the adapter 38 is threaded into the upper end of the shell 41 and then is secured in place by the pins 43. Next the first wire screen section 54 is inserted into the shell 41 which, for assembly purposes, is turned upside down. The upper end of the large diameter passageway 57 overlies the central depending flange 44. The second wire screen section 60, mounted on the cover disc or closure 48 around the metallic stud 64 and held in place by the director 68, next is inserted with the central conical section 69 projecting into the large diameter passageway 57. Finally the lower inturned end 47 is formed to the shape indicated at the lower end of FIG. 3 to securely hold the assembly in place.

The arrangement just described provides for a relatively streamline flow of the gas and are products from the discharge opening 58 in the terminal 28 through the large diameter passageway 57 and through the openings 74 in the director 68 for equal distribution through the interstices of the second wire screen 60. In addition as the are products and gas flow through the openings 74 into the wire screen section 60, a substantial amount of heat energy is absorbed therefrom. Also the central upper end of the section 69 acts as a stationary arc transfer terminal. Due to the cavity or pocket 81, the arc root centers in or around it and erosion due to direct impingement of the are products or the arc takes place here rather than on the first wire screen section 54 or the underlying screen section 60. Because the gas and are products are so well distributed with a relatively smooth flow pattern, the wire screen sections 54 and 60, and particularly the latter, are more efiiciently used. A substantial portion of the heat is absorbed before the gas and are products are discharged through the exhaust ports 50 in the cover disc or closure 48. The net result is a limited volume of relatively cool gases that is finally discharged at lower pressures with reduced flame and sound and shock waves as an incident to maximum value of the current flow that is interrupted by the interrupter 18. This makes the over all assembly much more suitable for relatively smaller and lighter enclosures, especially when higher interrupting capacities are required.

In FIGS. 7, 8 and 9 there are shown details of construction of a modified form of elongated condenser or muffier that is indicated, generally, at 84. It is arranged to be used in conjunction with a circuit interrupter 18 of the fuse type described hereinbefore having a continuous current rating of 400 amperes, a voltage rating of 15,000 volts, and an interrupting rating at this voltage of 40,000 a npcres. An adapter 85 is employed having an internal thread 86 for mounting the condenser or muliler 84 on the lower terminal 16 of the circuit interrupter 18. The adapter has a conical opening 87 and is threaded into an adapter extension ring 88 which, in turn, is threaded into the up per end of an elongated cylindrical shell 89 that may be formed of high strength metal such as steeel. At its lower end the shell 89 has a cover disc or closure 90 that may be formed of steel or brass. For example the closure 90 may be a copper alloy casting and it is provided with sector shaped openings 91. The lower end of the shell 89 is threaded at 92 for receiving the cover disc or closure 90.

At the upper end of the shell 89 and below the adapter extension ring 88 there is provided a first annular section 95 of wire screen. It is formed of the same material as the first annular section 54 of wire screen referred to hereinbefore. The section 95 of wire screen is wound so as to provide a large diameter passageway 96 into which the gas and are products from the circuit interrupter 18 are discharged on operation thereof to interrupt the circuit in which it is connected. Below and spaced from the first annular section 95 of wire screen is a second annular section 97 of wire screen which is relatively long. Both sections 95 and 97 of wire screen are juxtaposed to the inner surface of the shell 89 and substantially fill the same except for the large diameter passageway 96 in the former and a small diameter opening 98 in the latter. A metallic stud 99 of copper alloy substantially fills the small diameter opening 98 through the section 97 of wire screen. At its lower end the stud 99 is threaded as indicated at 100 in the cover disc or closure 90 centrally thereof. At its upper end the stud 99 is threaded, as indicated at 101, into the central section 102 of a gas or are products director 103. Thes arc products director 103 is formed preferably of high heat conductivity material such as cast cop per alloy. For the purpose of placing the large diameter passageway 96 in communication with the space below the gas or are products director 103 which is filled by the second annular section 97 of wire screen and the metallic stud 99, sector shaped openings 104 are provided between a rim 105 of the gas or are products director 103 and the central section 102 thereof. The sector shaped openings 104 are tapered from the side that faces the second annular section 97 of wire screen to a larger area opening at the upper end. The rim 105 is generally trapezoidal in cross section and it has a generally cylindrical surface 106 which has a snug fit with the juxtaposed inner surface of the shell 89. The sector shaped openings 91 in the cover disc or closure 90 are tapered similar to the taper for the openings 104 from a minimum at the outer side to a maximum at the top side.

The lateral dimension of each of the sector shaped openings 104 in the gas or are products director 103 along their pitch circle 107 is not substantially greater than the longitudinal dimension of each opening 104 at the pitch circle 107. The reason for this, as previously pointed out for the gas or arc products director 68, is to prevent the arc from looping downwardly past ribs 108 which interconnect the central section 102 and the rim 105 and impinging on the upper end of the screen section 97 therebelow. However, the area of the sector shaped openings 104 is such as to permit sufficient flow therethrough of the gas and are products that the back pressure in the bore 29 of the circuit interrupter 18 does not become excessive which would impede the exhaust from the bore 29 and would tend to prolong arcing.

It is important that the root of the are that is blown into the large diameter passageway 96 be held on the central section 102 of the gas or are products director 103 and not be permitted to wander to the first annular section 95 of wire screen or through the sector shaped openings 104 to impinge on the annular section 97 of wire screen therebelow. Accordingly, the passageway 96 in the first annular section 95 is larger than the exhaust opening 58 in the terminal 28 and is greater than the area of the central section 102 of the director 103. Further, the upper end 109 of the metallic stud 99 is threaded only part way into the central section 102 with the result that a cavity or pocket 110 is provided at the upper end in the central section 102 along the periphery of which the arc root tends to remain. Any erosion that takes place here can be readily accommodated since the central section 102 has a relatively large cross section as does the metallic stud 99.

Instead of threading the upper end of the metallic stud 99 into the central section 102 of the gas or are products director 103, the upper end of the metallic stud 99 can be juxtaposed to the underside of the central section 102 which would be imperforate but would have the cavity 110 formed in the upper side by drilling part way through. The principal reason for securing the ends of the metallic stud 99 to the cover disc or closure 90 and t the gas or are products director 103 is for convenience in assembly.

What is claimed as new is:

1. In a circuit interrupter means for establishing an arc and causing an exhaust flow of condensible gas and arc products at high temperature and pressure,

an elongated cylindrical shell joined to said are establishing means and providing a cylindrical chamber for receiving said exhaust flow at one end and centrally thereof,

a closure at the other end of said chamber secured to said shell and having exhaust ports venting said chamber to the atmosphere,

a first annular section of wire screen at said one end of said chmaber with its outer periphery juxtaposed to the inner surface thereof and its inner surface out of the direct path of said exhaust flow and defining a passgaeway having a relatively large diameter for receiving said exhaust flow,

a second annular section of wire screen in said chamber in engagement at one end with said closure, spaced at its other end from said first annular section, having its outer periphery juxtaposed to said inner surface of said chamber, and having a relatively small diameter opening extending centrally thereof, and

metallic are products director means interposed between the juxtaposed ends of said sections of wire screen, extending into juxtaposition with said inner surface of said shell, having a solid central portion in the direct path of said exhaust flow, and having openings therethrough between said central portion and the periphery of said director means for directing said exhaust flow from said relatively large diameter passageway in said first section of wire screen into said second section of wire screen to be cooled and condensed and to flow through said exhaust ports in said closure.

2. The circuit interrupter according to claim 1 wherein a metallic stud extends through said relatively small diameter opening in said second annular section of wire screen and substantially fills it, and

means secure one end of said stud to said closure and the other end of said stud to said arc products director means.

3. The circuit interrupter according to claim 1 wherein said are products director means has a circumferential rim that is juxtaposed to the inner surface of said shell and overlies said second annular section of wire screen.

4. The circuit interrupter according to claim 1 wherein said openings in said arc products director means are located between ribs that extend radially from said central portion thereof to a rim juxtaposed to said inner surface of said shell, and

the lateral dimension of each of said openings along their pitch circle is not substantially greater than the longitudinal dimension of each opening at said pitch circle.

5. The circuit interrupter according to claim 4 wherein said openings are sector shaped.

6. The circuit interrupter according to claim 1 wherein said are products director means has a central generally truncated conical section with the smaller end projecting into said relatively large diameter passageway.

7. The circuit interrupter according to claim 1 wherein said are products director means includes a central generally truncated conical section with the smaller end projecting into said relatively large diameter passageway,

a rim having a cylindrical outer periphery, and

ribs extending radially between said central section and said rim, said ribs decreasing in thickness from a maximum adjacent said second section of wire screen.

8. The circuit interrupter according to claim 1 wherein said are products director means is a circular metallic plate having ribs extending radially from said central portion thereof to a rim juxtaposed to the inner surface of said shell, and

said openings are located between said ribs and are sector shaped.

9. The circuit interrupter according to claim 8 wherein said ribs decrease in thickness from a maximum adjacent said second section of wire screen.

10. In a circuit interrupter means for establishing an arc and causing an exhaust flow of condensible gas and are products at high temperature and pressure,

an elongated cylindrical shell joined to said are establishing means and providing a cylindrical chamber for receiving said exhaust flow at one end and centrally thereof,

a closure at the other end of said chamber secured to said shell and having exhaust ports venting said chamber to the atmosphere,

a first annular section of wire screen at said one end of said chamber with its outer periphery juxtaposed to the inner surface thereof and its inner surface out of the direct path of said exhaust flow and defining a passageway having a relatively large diameter for receiving said exhaust flow,

a second annular section of wire screen in said chamber in engagement at one end with said closure, endwise from said first annular section, having its outer periphery juxtaposed to said inner surface of said chamber, and having a relatively small diameter opening extending centrally thereof, and

metallic are products deflector means interposed between the juxtaposed ends of said sections of wire screen, and having a solid central portion in the direct path of said exhaust flow, a cavity in said central portion opening toward said are establishing means to hold the arc root incident to operation of said circuit interrupter substantially in the vicinity of said cavity and openings placing said large diameter passageway in communication with said second section of wire screen,

11. The circuit interrupter according to claim 10 wherein said are products deflector means extends into juxtaposition with said inner surface of said shell and said openings are located between said central portion and the periphery of said deflector means for directing said exhaust flow from said relatively large diameter passageway in said first section of wire screen into the other end of said second section of wire screen to be cooled and condensed and to flow through said exhaust ports in said closure.

12. The circuit interrupter according to claim 11 wherein a metallic stud extends through said relatively small diameter opening in said second annular section of wire screen and substantially fills it, and

means secure one end of said stud to said closure and the other end of said stud to said are products director means.

13. The circuit interrupter according to claim 11 wherein said openings in said are products director means are located between ribs that extend radially from said central portion thereof to a rim juxtaposed to said inner surface of said shell, and

the lateral dimension of each of said openings along their pitch circle is not substantially greater than the longitudinal dimension of each opening at said pitch circle.

14. The circuit interrupter according to claim 11 wherein said are products director means has a central generally truncated conical section with the smaller end projecting into said relatively large diameter passageway.

15. The circuit interrupter according to claim 11 wherein said are products director means includes a central generally truncated conical section with the smaller end projecting into said relatively large diameter passageway,

a rim having a cylindrical outer periphery, and

ribs extending radially between said central section and said rim, said ribs decreasing in thickness from a maximum adjacent said second section of wire screen.

16. The circuit interrupter according to claim 11 wherein said are products director means is a circular metallic plate having ribs extending radially from said central portion thereof to a rim juxtaposed to the inner surface of said shell, and said openings are located between ribs and are sector shaped. 17. The circuit interrupter according to claim 11 wherein said ribs decrease in thickness from a maximum adjacent said second section of wire screen.

References Cited UNITED STATES PATENTS 1,502,881 7/1924 Sandin 200l20 2,091,423 8/1937 Triplett 200l 17 2,319,277 5/1943 Triplett 2001l7 X 3,178,537 4/1965 Patterson 200120 3,230,331 l/l966 Lindell 220-120 BERNARD A. GILHEANY, Primary Examiner.

H. B. GILSON, Assistant Examiner. 

